[GreenKeys] Extel Musings...more

[Sheldon Daitch]

The RO Extel units had one interesting advantage over
the M-15 or other units, in that the tone receive modem
would fit into the Extel case.  Or at least it had provisions
for an optional tone unit.  This internal tone modem was
not the typical Lenkurt tone unit that was found under
the M-15 printers.

There were some differences in the the RO units, too, in that
some of them had a set of position sensors for the print head.
The print head would contact a metal blade at each end of the
print head travel.  If the typed line did not have a CR, the
print head would contact the right hand blade, which forced
an electronic CR-LF and a buffer would store characters
until the print head reached the left hand margin and contacting
the corresponding metal blade, at which point the print head
stepper motor would then start the print head across the page
and the character buffer would then output characters to the
print head.

The game, at least on the 66 WPM UPI printers was to hold
the print head on a CR to keep it from hitting the left margin and
let the buffer store characters, and then, release the print head,
and it would zip across at about 50 per cent faster printing.

I think the buffer would hold at least three full lines worth of
characters, and eventually, the printing would "catch" up with
the input from the wire service.